Q: My biggest thing is categories. That's the biggest thing holding me up right now. Like if I make a 2015-20 Mustang bucket, can you click that then click clutches. Etc.
A: Yes, the buckets can provide collections like "2015-20 Mustang Bucket". From there you could use a plugin to provide other search details and navigation. I've seen people using Buddha Mega Menu, for example. Fitment search is also another way to fill the gap. Alternatively you can simply use the fitment based collection as a collection link in the native page editor.